It is now widely diffused, in sailing races, to make use of highly sophisticated crafts and sailing equipment--as masts of light metal alloys, light and strong sailcloths, thin ropes for the standing and running rigging, composite structures for the masts and hulls--so as to obtain valid competitive results in regattas.
The present invention concerns a mast for sailboats with improved characteristics.
As known, the possibility for a sailboat to sail up to windward greatly depends--in boats with conventional equipment, and other conditions being equal--not only on the lightness of the mast, but also and above all on the fact of constructing it with a small cross section area, so as to prevent wakes and whirlwinds (diagrammatically indicated by T in FIG. 1 of the accompanying drawings).
It is however possible to eliminate the whirlwinds created by the mast, thereby increasing its efficiency, by making the structure of the sail more complex, for instance in the form of a wing incorporating the mast A (as diagrammatically indicated in FIG. 2 of the accompanying drawings). This solution allows in fact to emphasize the camber of the extrados in respect of the intrados camber, so as to increase--according to the Bernoulli theorem--the air speed Ve in respect of Vi, and thereby improve the lift S2 and the useful wind thrust F3.
An attempt in this sense has already been made in the past, but this solution involved such complications as to make its application rare and difficult. In practice, this solution has been adopted only on some regatta catamarans: "Miss Lancia" was using for example a mast with two sailcloths (FIG. 3) having inner elastic wingribs and apt to be worked by means of ropes so as to form a wing contour, which thus became symmetrical on the two sides.
A solution of this type is for example described in the FR-A-2.555.957, wherein the mast is on one hand mounted rotating about its axis and, on the other hand, it has a contour apt to be radiused to the two sailcloths, so as to form therewith essentially a wing contour with a symmetrical leading edge (see, in particular, FIGS. 3 and 4 of the FR-A-2.555.957).
On the other hand, it is also a known and now diffused custom, on yachts as well as on regatta boats, to furl the sail VE inside the mast A (FIGS. 5 and 6), rolling it up around a vertical rotary mandrel P positioned along the axis of the mast, so as to avoid the manual work of shortening the sail in the traditional way with reefs, as the wind increases its force. For this purpose the mandrel P, inserted into a cavity C of the mast A, is rotated by hand (with a handle and suitable transmission) or by means of electric and/or hydraulic motors. FIG. 7 of the drawings is a very clear enlargement of a typical shape of the cross section of one of these masts A (as described, for example, in the EP-A2-0076878).
A still different construction was adopted on "Icarus", wherein the rotary mast AR had a cross section extending and tapered towards the stern (FIG. 4), with a single sailcloth t behind the mast, but wherein the tapered surface of the rotary mast reduced the whirlwinds and allowed, in cooperation with the sailcloth, to approach the wing shape. A solution of this type is proposed, for example, in the DE-A-1.921.628.